spec: reload @copy_from before running course copy

Change-Id: I665039ddbe181c1a36ab69267e7261798caaa762
Reviewed-on: https://gerrit.instructure.com/29211
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>